The present invention relates to a camera for photogrammetry to be installed on a small flying vehicle and an aerial photographic device provided with the camera for photogrammetry.
In recent years, with the progress of UAV (Unmanned Air Vehicle), a camera for photogrammetry is installed on UAV and there has been developed a technique of photogrammetry using the UAV.
Normally, an UAV makes flight by tilting the vehicle body in forwarding direction, while tilting of the vehicle body of the UAV is very likely to be influenced by the speed of propulsion and by wind, and stability of the tilting is low. On the other hand, in aerial photogrammetry, it is necessary to highly precisely photograph the images in vertical and downward direction, and the stability of the tilting of the camera is required.
For this reason, normally, in aerial photographing, a gimbal, which is driven and controlled, is mounted on a vehicle body of the UAV, and aerial photographing is performed by installing the camera on the gimbal to stabilize the direction of the camera, and to perform aerial photogrammetry based on aerial photographs thus taken.
As one of the methods to perform the orientation to the ground (absolute orientation) on aerial photograph taken in the conventional aerial photogrammetry, there is a method of using ground coordinates measured by a Global Positioning System (GPS) or by a total station.
Also, it is conceivable to install GPS on the vehicle body of UAV, to measure an absolute coordinate of the vehicle body at the time of photographing by GPS, and to perform absolute orientation of the vehicle body based on the measured ground coordinates.
However, because GPS is installed on the vehicle body of UAV and the camera for photogrammetry is installed on the vehicle body via a gimbal, the GPS and the vehicle body is integrated, and the camera for photogrammetry is directed in vertical direction regardless of the posture of the vehicle body, therefore, relative positional relation between GPS and the camera for photogrammetry is changed according to the change of posture of the vehicle body.
Further, the posture of UAV is constantly changing due to the causes such as speed of propulsion, wind, etc., and UAV is moving even in the condition of stationary flight (in hovering state). Therefore, relative positional relation between GPS and the camera for photogrammetry is also constantly changing, and it was difficult to accurately measure the position of the camera for photogrammetry at the time when aerial photograph is taken.